Temperature indicating device



g- 1954 R. H. AMUNDSON ETAL 2,535,903

TEMPERATURE INDICATING DEVICE Filed Dec. 30, 1952 INVENTOR. Roald HJqmundaon, 291.01- smelljer Patented Aug. 17,1954

OFFICE TEMPERATURE, INDICATING navron Roald H. Amundson,

Smeltzer, South McGraw Electric Company, corporation of DelawareApplication December30, 1952, SerialNo. 328,748

(o1. s4o 227) 6 Claims.

This invention relates generally to a temperature indicating device, andmore particularly to anindica'ting device adapted for mounting upontheexternal surface of a tank-wall of a container to indicate attainmentof certain predetermined temperatures.

An object of the present invention is to provide awtemperaturejindicating device adapted for mounting externally of a containertank-wall, which device includes a temperature responsive actuatorelement as a means for releasing an indicating means provided with awarning signal which is readily perceptible from a distance on theattainment of a predetermined tank-wall temperature. H

Another object of this invention is to provide a temperature indicatingdevice adapted for mounting externally of a container tank-wall, which"device includes a temperature responsive actuator element that'iscompensated for ambient temperature variations and which releasablyretainsan indicator member in a first position prior to movement to asecond position and which indicator member may be further provided witheither an audible or visible warning signal perceptible from a distanceon the attainment of a predetermined tank-wall temperature.

. Referring nowto the drawing:

Fig. l is a side elevational view of the indicating, device, illustratedpartly in section, and

mounted on a container tank-wall.

Fig.2 is a fragmentary front elevational view of the device, illustratedpartly in section.

Fig. 3 is an elevational view of the indicator actuator element for thedevice. .Fig l is an enlarged top view of the movable indicator element.

. Throughout the several views, like parts are referred to by the samereference characters.

The thermally controlled temperature indicating device, is preferablymounted directly on atank-wall T having a removable cover C and a gasketG, being shown in fragmentand in section. a

The novel indicating device comprises a hous- Jing I closed at the topand opened at the bottom, and including integral mounting tabs or lugs 2provided withopenings for receiving bolts 3 for direct mounting to atank-wall. Mounting means utilizing conventional mounting straps .orbrackets may also be used (not shown).

The housing is preferably of insulating material which may beconveniently molded in the desired shape. Thus, heat transmitted fromthe tank wall will be prevented from being conducted with an L-shapedlatch spring 2|.

Milwaukee, Wis., and Paul Bend, Ind.,

assignors to Milwaukee, Wis., a

a bimetallic material as a convenient means-of.

supplying a rotative motion at its center. The

outer end of the spiral actuator 4 is secured to a metallic heatconducting ring 5, which contacts or may be integrally formed with acover plate 6; The device is mounted in a manner which m vides intimatecontact between the conducting cover plate 6 and the tank-wall T. Thus}the heat transmitted by the tank-wall will be conducted directly to theactuator 4.

A weather-tight mounting gasket 1 is provided between the housing andthe plate 5. The gasket also'acts to provide a means for directing heataway from the housing and towards the actuator 4. The innermost end 8 ofthe actuator 4 is arranged to be fastened to a drive shaft 9, at least aportion In of which is of insulating material. The drive shaft isrotatively supported by a bush ing member II and terminates at itsopposite end in an ambient temperature compensator l2.

It will be obvious that the compensator I2 should preferably be ininsulating relationship to theactuator to provide a true indication ofambient temperatures effecting the device. The drive shaft 9 may thus befabricated entirely of insulating material having sufiicient strengthtransversely of its axis, or may include the portion ID of heatinsulating material. The shaft is rotatively supported at thecompensator end by means of a bushing [3. The ambient temperaturecompensator is also preferably of a spiral shape and fastened to andprotected by a cup-like cover plate l4 fastened to the housing I, andincluding a weather-tight gasket l5. The cylindrical drive shaft 9 isnotched intermediate its ends to provide a latch release surface 5 forpurposes hereinafter described. l

A visible indicating means is provided by the indicator 20, which ispreferably tubular in construction, but which may be of a solid crosssection and remain within the scope of the present invention. Theindicator is slidably received within the bore of the housing I and isprovided The latch spring is provided with a detent portion 22 arrangedto normally engage the drive shaft 9 at its periphery, and is preferablypositioned in the proximity of the notched surface IS. A pin 23 ismounted on the upper surface of the in dicator 20 and is slidablyreceived by a well-like opening 24 of the housing I. A compressionspring 25 is positioned on the pin and acts to bias the indicator in adownward direction, as viewed in Figs. 1 and 2. The lower end of thehousing I is preferably enclosed by means of a floor plate 26, whichincludes an opening 21 for slidably receiving the indicator 20. Theindicator is preferably provided with opposed notches 28 adapted'to bereceived by guide ribs 29 extending substantially coextensive lengthwiseof the housing.

The preferred embodiment of the novel device includes a visible warningsignal incorporated in the indicator in the form of an electric lamp 30,which is threadingly orotherwise releasably en gageable with aconventional conducting socket member 3|. The indicator 20 may be cutaway to provide an opening 32 on either side thereof for thetransmission of light from the signal lamp 30, or the indicator itselfmay be made of a light transmitting material, such as a transparentplastic or glass. A threaded cap 33 is provided as a removable closurefor the indicator to permit access for replacement of burnt out lamps,and other routine maintenance operations.

The present embodiment is arranged for electrical connection with asupply source (not shown), This connection is made through the leads 34and 35 and through the terminals of an exepndible protective fuse 36 andresilient contact members 3'5. These contact members are stationarilymounted on an insulating support 38 in spaced relationship. The contacts31 are adapted to electrically engage the indicator contacts 39 and 49when said indicator is released to indicating position as willhereinafter be described.

It will be apparent that a relatively inexpensive device, from amanufacturing standpoint, may be provided by substituting a reflectiveouter coating on the indicator 20 for the warning lamp 30. Thus, theindicator may take the form of a solid plug-like member having areflective coating in the form of a brightly colored surface and/or anyof the commercially available luminous or luminescent surface coatings.Coating materials of this nature may also be applied as additionalsignaling means to indicators having electrically actuated warningdevices such as the lamp 30. It will also be apparent that audiblesignaling means may be used with or substituted for the lamp 30 andremain within the scope of the present invention.

It has been found to be desirable to provide an insulating projection 42on the housing I for spacing the housing from the tank-wall T to permitthe transmitted heat to be conducted directly to the actuator 4 from theplate which is preferably in intimate contact with the tank-wall.

Any of the above-mentioned embodiments will operate substantially in thesame manner and respond to predetermined temperatures affecting thetank-wall T as transmitted to the heat conducting plate 6. On theoccurrence of a tankwall temperature of a value exceeding or equal to apredetermined value, the spiral bimetallic actuator 4 will cause thedrive shaft 9 to rotate in a counterclockwise direction, as viewed inFig. 2. On reaching the predetermined temperature the shaft will haverotated to a position which will permit the latch spring detent 22 toclear the shaft 9 in the notched area It. This will permit the indicator20 to drop downwardly due to the forces of gravity exerted thereon andthe pressure of the spring .25 reflected in the r perature compensatorf0! pin 23. the overhanging portion 4| rests on the floor plate 26,thereby exposing the indicator to visible perception. In the preferredembodiment the indicator contacts 39 and 40 will engage the contacts 31and cause the lamp 30 to be energized to provide an additional warning asignal. After the tankwal1 T has cooled to a temperature below thepredetermined value, the shaft 9 will have been rotated by thebimetallic actuator 4 to the position shown in Fig. 2. Hand pressure onthe closure 33 of the indicator will force the indicator upwardly untilthe latch spring 2| passes the notched portion and the detent 22 engagesthe shaft 9. The pin 23 will engage the opening 24 to cause a slightdownward pressure on the indicator for providing a stable engagement inthe housing 1. The device is now ready for another cycle of operationsshould the tank-wall temperature again reach the predetermined value.

We claim:

1. In a temperature indicating device including an indicator memberbiased for movement from a first position to a second position andincluding a set of normally disengaged electrical contacts and anelectrically operated warning device, a second set of electricalcontacts arranged for connection with an electrical supply source andarranged for electrical engagement with said first mentioned electricalcontacts on movement of said indicator member to said second position,and a thermally responsive indicator member retaining means comprisingin combination a thermally responsive actuator, an ambient temsaidactuator, a latch means operatively associated with said actuator andnormally releasably engaging said indicator member in said firstposition, said latch means being movable towards release position on theoccurrence of a predetermined temperature value efiecting said actuatorto affect the movement of said indicator member to said second position.

2. In a temperature indicating device including an indicator memberbiased for movement from a first position to a second position andincluding a set of normally disengaged electrical contacts electricallyconnected to a warning signal device, a second set of electricalcontacts arranged for connection with an electrical supply source andfor electrical engagement with said first mentioned electrical contactson movement of said indicator member to said second position, and athermally responsive indicator member retaining means comprising incombination a thermally responsive actuator, an ambient temperaturecompensator for said actuator, a latch means operativel associated withsaid actuator and nor mally releasably engaging said indicator member insaid first position. said latch means being movable towards releaseposition on the occurrence of a predetermined comp nsated temperaturevalue effecting said actuator to afiect the movement of said indicatormember to said second position.

3. In a temperature indicating device including an indicator memberhaving a latching d e tent and being biased for movement from a firsposition to a second position, a thermally responsive indicator memberretaining means comprising in combination a thermally responsivebimetallic actuator, an ambient temperature compensator for saidactuator, a drive shaft havin a transverse notched portion intermediateits ends. said shaft being rotatively operated by said actuator, saiddetent on said indicator member The indicator will continue to dropuntil normally releasably engaged with said drive shaft and freelyslidable in said notched portion for latching disengagement with saidshaft, said drive shaft .being rotatively movable towards disengagementwith said detent on the occurrence of a predetermined compensatedtemperature value effecting said bimetallic actuator to aifect themovement of said indicator member to said second position.

4. In a temperature indicating device including an indicator memberhaving a latching detent and being biased for movement from a firstposition to a second position and further including a set of normallydisengaged electrical contacts electrically connected to a warningsignal device, a second set of electrical contacts arranged forconnection with an electrical supply source and for electricalengagement with said first mentioned electrical contacts on movement ofsaid indicator member to said second position,

a thermally responsive indicator memberretaining means comprising incombination a thermally responsive bimetallic actuator, a drive shafthaving a transverse notched portion intermediate its ends, said shaftbeing rotatively operated by said actuator, said detent on saidindicator member normally releasably engaged with said drive shaft andfreely slidable in said notched portion for latching disengagement withsaid shaft, said drive shaft being rotatively movable towardsdisengagement with said detent on the occurrence of a predeterminedtemperature value effecting said bimetallic actuator to affect themovement of said indicator member to said second position.

5. In a temperature indicating device includ ing an indicator memberhaving a latching detent and being biased for movement from a firstposition to a second position and further including a set of normallydisengaged electrical contacts electrically connected to a, warningsignal device, a second set of electrical contacts arranged forconnection with an electrical supply source and for electricalengagement with said first mentioned electrical contacts on movement ofsaid indicator member to said second position, a ther- 4 mallyresponsive indicator member retaining means comprising in combination athermally responsive bimetallic actuator, an ambient temper-aturecompensator for said actuator, a drive shaft having a transverse notchedportion intermediate its ends, said shaft being rotatively operated bysaid actuator, said detent on said indicator member normally releasablyengaged with said drive shaft and freely slidable in said notchedportion for latching disengagement with said shaft, said drive shaftbeing rotatively movable towards disengagement with said detent on theoccurrence of a predetermined compensated temperature value effectingsaid bimetallic actuator to affect the movement of said indicator memberto said second position.

6. In a temperature indicating device including an indicator memberhaving a latching detent and being biased for movement from a firstposition to a second position and further including a set of normallydisengaged electrical contacts electrically connected to a signal lamp,a second set of electrical contacts arranged for connection with anelectrical supply source and for electrical engagement with said firstmentioned electrical contacts for energizing said lamp on movement ofsaid indicator member to said second position, a thermally responsiveindicator member retaining means comprising in combination a thermallyresponsive bimetallic actuator, an ambient temperature compensator forsaid actuator, a drive shaft having a transverse notched portionintermediate its ends, said shaft being rotatively operated by saidactuator, said detent on said indicator member normally releasablyengaged with said drive shaft and freely slidable in said notchedportion for latching disengagement with said shaft, said drive shaftbeing rotatively movable towards disengagement with said detent on theoccurrence of a predetermined compensated temperature value effectingsaid bimetallic actuator to affect the movement of said indicator memberto said second position.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,405,251 Anderson Jan. 31, 1922 1,668,388 Treander May 1,1928 2,457,881 Fisher Jan. 4, 1949

